Differentiating early-stage nasopharyngeal carcinoma from adenoidal hypertrophy via SLC40A1 expression and developing a prognostic model for disease progression.

OBJECTIVE: To investigate the expression and diagnostic utility of solute carrier family 40 member 1 (SLC40A1) in differentiating early diagnosis of nasopharyngeal carcinoma (NPC) from adenoid hypertrophy (AH), and to develop a prognostic prediction model based on its expression. METHODS: Public databases were used to analyze SLC40A1 expression in head and neck squamous cell carcinoma (HNSC) and its association with prognosis, pathological staging, and immune infiltration. A total of 102 NPC patients, 97 AH patients, and 101 healthy controls were enrolled between October 2021 and October 2023. SLC40A1 expressions in tissues and serum were assessed via real-time reverse transcription polymerase chain reaction and Western blotting. Associations with clinicopathological features were evaluated. Receiver operating characteristic (ROC) curves evaluated diagnostic performance. Logistic regression identified prognostic factors, and a predictive model was constructed. RESULTS: Bioinformatics analysis indicated downregulated SLC40A1 in HNSC, negatively associated with tumor (T) stage and distant metastasis (M) stage. Clinical validation showed significantly lower SLC40A1 mRNA and protein levels in NPC compared to AH and controls, with negative correlation to Epstein-Barr virus (EBV) infection (all P<0.05). Serum SLC40A1 mRNA demonstrated 90.20% sensitivity and 62.38% specificity for NPC diagnosis. When combined with EBV DNA, it yielded an improved diagnostic performance (AUC=0.913). Tumor diameter >5 cm and lymph nodes ≥2 were independent risk factors for NPC progression, while high SLC40A1 expression was protective (OR=0.140, 95% CI: 0.028-0.700). The final model achieved 91.67% sensitivity and 72.00% specificity (AUC=0.863). CONCLUSION: SLC40A1 is significantly downregulated in NPC and may serve as a diagnostic and prognostic biomarker, especially when combined with EBV status.